TM 5-2420-232-10
0003
BRAKING SYSTEM
0003
1.
Service Brakes (Foot Brake) - A service brake system consisting of an air-over-silicone-based hydraulic brake fluid sys-
tem with electronic ABS and a load sensing valve which reduces rear axle braking effort in proportion to rear axle load.
The front axle has a pair of 2.36-in. (60-mm) diameter piston calipers and a pair of 2.95-in. (75-mm) diameter piston cali-
pers (one of each on each side comprises a pair). Each pair has hydraulic fluid provided by a single air/hydraulic actuator.
The rear axle has a pair of 2.36-in. (60-mm) diameter piston calipers and a pair of 2.95-in. (75-mm) diameter piston cali-
pers, each with its own air/hydraulic actuator. Electronic ABS system has a wheel speed sensor on each wheel, all front
calipers are controlled by single modulator, but both rear calipers each have their own modulator. Air is supplied from an
engine-mounted and engine-powered compressor. The compressed air is cooled by a cooler assembly mounted on top of
the main cooling pack and dried by an electronic dryer with automatic drain. An automatic 4-way circuit protect valve
preferentially distributes the compressed air through the system (service brakes first, then parking brake, and ancillary cir-
cuits) and isolates individual circuits in the event of failure. A quick release valve is installed to ensure the required front
caliper release times are achieved. Air tank volume is 55.6 pt (30.6 L) for the front axle and 27.8 pt (15.3 L) for the rear;
front and rear tank pressures are independently monitored on air gauges. The operator is further alerted to low air pressure
by visible and audible alarms on the EMS unit.
Parking Brake - Two transmission-mounted discs and calipers independently provide park braking for the front and rear
2.
axles. Calipers are spring apply, hydraulic release. The hydraulic release pressure is supplied by the machine s hydraulic
system and is controlled by a cab-mounted control button operating a pneumatic valve which delivers a signal to a pneu-
matic/hydraulic relay.
0003-9
